Parr Instrument Series 3900 - Manual (Page 6)

Hydrogenation Apparatus
P a r r I n s t r u m e n t C o m p a n y 6
Assembly Instructions
Rinse or blow air through the hydrogen tank to
remove any dust or foreign material. Likewise, blow
out the gas hose and valves to be sure that they are
dust-free and clean.
Set the apparatus on a sturdy bench or table where
there is convenient access to an electrical outlet with
the appropriate supply voltage and current ratings
in accordance with national and local electrical code
requirements. The supply voltage must not exceed
the marked nominal voltage shown on the instru-
ment by more than 10%. The supply voltage recep-
tacle must have an earth ground connection.
Attach the valves to the hydrogen tank and tighten
the couplings fi rmly with a wrench. This tank is fi lled
through the AA92CA valve which is attached to the
right end. The gage on this valve shows the tank
pressure when the valve is closed. The gage on the
3A93CA valve at the left end of the tank shows the
pressure in the reaction bottle and connecting tube.
The front knob on the 3A93CA valve controls the
fl ow of gas from the tank to the bottle. The rear knob
at the opposite end of the block is used when dis-
charging gas from the bottle or when evacuating the
bottle through the hose nipple.
The 25-inch length of polypropylene tubing leading
to the reaction bottle must be fi rmly connected to
the outlet fi tting on the 3A93CA valve. No special
clamps or fi ttings are required to fasten this tube
into the bottle stopper. Simply slide the end of the
tube through the 61CA4 washer and through the
166CA retaining ring, then push the tube through
the one-hole Neoprene stopper leaving a projection
of about one inch below the bottom of the stopper.
Slide the safety screen over the bottle; place the
bottle into the holder and tighten the thumb nuts on
the ends of the two tie rods. The clamping pressure
developed by the thumb nuts will hold the bottle in
the shaker mechanism and it will also anchor the
connecting tube in the stopper.
A 6-ft hose (A118CA) is furnished for connecting the
apparatus to the pressure regulator or needle valve
on a commercial hydrogen tank. Screw one end of
the hose into the socket in the AA92CA valve and
connect the other end to the pressure regulator or
tank valve. The 1/8” NPT pipe threads on the ends of
the pressure hose should be coated with Tefl on tape,
plastic lead or other thread dope to ensure tight
seals. The 1/8” to 1/4” bushing can be removed from
the hose if it is not required but do not unscrew the
fi ttings which anchor the end nipples to the hose
itself.
Before using a new apparatus for the fi rst time,
assemble it with an empty bottle and test for gas
leaks, as follows: Fill the tank with hydrogen to
40 psig; then close the tank fi lling valve. Open the
bottle valve and allow the full tank pressure into
the bottle; then close the bottle valve. The tank and
bottle gages should now read the same. Record
these pressures and continue to observe them over
a period of four to six hours. The pressures should
remain constant throughout this period unless there
is a signifi cant change in room temperature. If a
noticeable drop is observed in either gage, fi nd and
correct the leak before starting to use the apparatus.
Any leaks can usually be detected by brushing the
joints with a soap solution.